Testing And Benchmarking in Lua

Here’s the translation of the Go testing and benchmarking example to Lua, formatted for Hugo:

-- Unit testing is an important part of writing principled Lua programs.
-- Lua doesn't have a built-in testing framework, but we can use a popular
-- third-party library like busted for unit testing.

-- For the sake of demonstration, this code is in a single file,
-- but it could be split into separate files. Testing code typically
-- lives in a separate file from the code it tests.

-- We'll be testing this simple implementation of an integer minimum.
local function int_min(a, b)
    if a < b then
        return a
    end
    return b
end

-- To use busted, we need to wrap our tests in a describe block
describe("int_min", function()
    -- A test is created by using the it function
    it("returns the minimum of two numbers", function()
        local ans = int_min(2, -2)
        -- assert is used to check conditions
        assert.are.equal(-2, ans)
    end)

    -- Writing tests can be repetitive, so it's idiomatic to
    -- use a data-driven style, where test inputs and
    -- expected outputs are listed in a table and a single loop
    -- walks over them and performs the test logic.
    it("handles various input combinations", function()
        local tests = {
            {a = 0, b = 1, want = 0},
            {a = 1, b = 0, want = 0},
            {a = 2, b = -2, want = -2},
            {a = 0, b = -1, want = -1},
            {a = -1, b = 0, want = -1},
        }

        for _, tt in ipairs(tests) do
            local ans = int_min(tt.a, tt.b)
            assert.are.equal(tt.want, ans)
        end
    end)
end)

-- Lua doesn't have built-in benchmarking tools like Go,
-- but we can create a simple benchmarking function
local function benchmark_int_min()
    local start = os.clock()
    for i = 1, 1000000 do
        int_min(1, 2)
    end
    local elapsed = os.clock() - start
    print(string.format("BenchmarkIntMin: %.6f seconds", elapsed))
end

-- Run the benchmark
benchmark_int_min()

To run the tests and benchmark:

$ busted test_file.lua
●●
2 successes / 0 failures / 0 errors / 0 pending : 0.001196 seconds

$ lua test_file.lua
BenchmarkIntMin: 0.062500 seconds

In this Lua version:

We use the busted testing framework, which is a popular choice for Lua. It provides a structure similar to many modern testing frameworks.
The describe and it functions are used to organize and define tests, similar to the TestIntMinBasic and TestIntMinTableDriven functions in the Go version.
We use assert.are.equal for assertions, which is similar to the t.Errorf in Go.
Lua doesn’t have built-in benchmarking tools like Go, so we created a simple benchmarking function that measures the time taken to run the int_min function a million times.
The output format is different from Go’s, but it provides similar information about test success and benchmark performance.

Remember to install the busted framework (luarocks install busted) before running the tests. The benchmark can be run with the standard Lua interpreter.

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Testing And Benchmarking in Lua